One staircase, three experiments: sum the demands, then burn a car, add two, or add a buyer Sum the demands A car burns Two cars arrive A new buyer joins 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 1 2 3 4 5 6 7 8 9 10 Quantity of cars Price ($ thousands) old price, $7,000 D A C B T = A + B + C + D T (before E) T = A + B + C + D + E S S before S after supply falls S before S after supply rises market clears at 7 cars, $7,000 7 wanted, 6 exist — shortage demand rises At $7,000: A wants 2, B wants 1, C wants 2, D wants 2 — market demand 7. The four demands sum sideways to 7 — exactly the seven cars, so the market clears. Press a button to rerun the market: burn a car, let two more arrive, or add a new buyer. In each rerun the dashed line is the old $7,000 price, and the gap shows why it cannot hold.